Femara (Letrozole) is a non-steroidal selective third generation aromatase inhibitor. The structure and activity of this compound are very similar to that of Arimidex (anastrozole), and it is prescribed for similar medical purposes. More specifically, U.S. prescribing guidelines for Femara (Letrozole) recommend it be used for the treatment of postmenopausal women with estrogen receptor-positive or estrogen receptor-unknown (unsure if the cancer is responsive to estrogen) breast cancer. It is typically used as a second line of treatment after an estrogen-receptor antagonist like tamoxifen has failed to elicit a desirable response, although it is sometimes initiated as the first course of therapy depending on the circumstances. Male bodybuilders and athletes find value in Femara (Letrozole) for its ability to mitigate the estrogenic side effects associated with the use of aromatizable anabolic/androgenic steroids, such as gynecomastia, fat build up, and visible water retention. Femara (Letrozole) represents one of the newer achievements in a long line of drugs targeting aromatase inhibition. It is among the most potent estrogen - lowe ring d rugs developed to date, and has an effect significantly stronger than non-selective first generation aromatase inhibitors like Teslac and Cytadren. The dosage of each tablet of Femara is 2.5 milligrams, which according to product information was sufficient to lower estrogen levels by an average of 78% during clinical trials. The drug, however, appears to often remain quite effective in lower doses. The package insert for the product itself comments that during clinical studies doses as low as . 1 and .5 milligrams produced 75 a n d 78% estrogen inhibition, respectively in many patients. The recommended dose, likewise, reflects a level that seems to elicit a desired level of inhibition in nearly all patients. A large number of people may, therefore, respond well to lower doses of the drug.